climate and vegetation vary with latitude, many species are restricted by to specific latitudes

polar bears, mangroves

Altitude

altitude has an effect similar to latitude

mountain goat

Fire frequency

some species require fire as part of their life cycle

jack pine

Soil

different types of soil have different types and quantities of nutrients

wheat, rice

Aquatic organism have some additional factors:

Factor

Description

Examples

Water currents

Speed of water can affect where an organism lives

salmon, perch

Dissolved oxygen

Fish do not breathe air, but instead take dissolved oxygen out of the water

Dissolved nutrient

Nutrient requirement vary widely between organisms

Suspended soils

Soil and other particles suspended in the water can reduce the amount of sunlight penetrating the water

Limiting factors

Limiting Factor

One factor which is more important than other factors in determining the success of a population

Example 1 If there is enough water, shelter, and space for 20 rabbits, but only food for 10; then the rabbit population will not exceed 10.

Example 2 If there are food for 1000 birds, but nesting sites for 100, the population of birds will be limited.

In Examples 1 and 2, food and nesting sites are the limiting factors, respectively.

Habitat and Niche

Definitions

Habitat

the place where a population lives

Niche

(pronounced nitch) is the role which a species has within an ecosystem.

Note that the habitat can be considered the address and the niche as the occupation.

Niche

Broad versus Narrow

Generalist species - Broad niche

lives in many different places, eats a variety of food, or tolerates wide range of environmental conditions

examples: cockroach, humans, dogs

Specialist species - Narrow niche

lives in only one type of habitat, tolerates narrow range of environmental conditions, or uses only one or a few types of food

example: giant panda (eats only bamboo)

Tolerance

Species have a specific range of tolerance to physical, chemical, and biological conditions and resources.

This range forms the fundamental niche.

However, pressures from other species form a narrower niche, called a realized niche.

Niche Differentiation

The key to understanding the concept of niche is understanding why different niches exist.

Competitive Exclusion Principle

Two species competing for the same resource cannot coexist if other ecological factors are constant

In other words, different species cannot exist in the same niche. How different niches can live in the same area is due to resource partitioning

Resource Partitioning

Dividing up resources so that species do not directly compete

Types of resource partitioning:

Temporal - species compete for same resources at different times

Example: hawks hunt during the day, owls hunt at night

Spatial - species occupy different areas

Examples:

Different species of warblers feed in different parts of the same trees

Giraffes feed at the top of trees, while deer and antelope feed near the bottom of the tree

Food Chains

A food chain is a series of organisms each of which is a source of food for the next one

Trophic level

each level in a food chain

Major roles

Producers

Organisms which use energy to produce their own food

Consumers

Organisms which get their food by consuming other organisms

Primary consumers or Herbivores

Animal that eat producers

Secondary consumers or Carnivores

Animal that eat other consumers

Omnivores

Animals which are both herbivores and carnivores

Decomposers

Organisms which get their energy from dead organic matter

Food Webs

The description of a food chain is too simplistic. Organism eat many other organisms. This leads to a further concept.

Food web

A food web is a set of interconnected food chains

Energy Flow

As energy is transferred through the food chain, the concept of energy flow applies.

Energy flow through a food chain

The efficiency of each trophic level is about 5 - 20%. (10% is typical).

This means that carnivores have about 1% of the energy that plants capture.

The energy can be described in terms of biomass

This energy flow has an effect on the number of organisms at each level.

Energy Pyramid show decreasing biomass and number of species per trophic level

Activity

Purpose:An important part of science is the abililty to observe and take notes.

Objectives: Observe wildlife in order to appreciate ecology and to hone your observation skills.

Activity: Go to either a park or to a wildlife area where there is little outside disturbances (such as cars or people). Then sit quietly for about two hours observing all around you and take notes of everything you see and hear.

Note:This could be done individually or in groups. However, groups of more than three can make the activity difficult. Follow your instructors guidelines.

Hints: You may not see any activity at first, but after a while things will start to appear. Do not forget to note the physical environment, plants, and insects. It is also important to look at the interactions between organisms.

Notes

↑This is the technical definition. The common definition is all organisms of the same "type"